Room Acoustics .....again

[jyc]

Hi,

I know there seems to be a few of these around here, but i guess every room's different. :D

I'm currently thinking about buildling my own acoustic panels and would like some advice as to what materials to use. I've read the other thread by Cojo about him building "bass traps" using rock wool. And I was wondering if it can be used as a broad-frequency absorption or just for bass specifically? (I am quite a newbie in this and tbh I don't even know what rock wool is and where I could get them (I live in Hong Kong) but I'll have to sort them out myself).

My room is about 8.5 feet x 10.5 feet with a 9 feet ceiling. I guess this won't be the best room in the world as it's nearly a cube shape. But it's what I've got to work with. Any suggestions will be helpful.

Oh, and also, I'm thinking of placing my monitor along the longer wall, is that gonna be a problem?

I've attached a sketch.

Thanks a lot.
Jyc

[Cojo]

Hi jyc.

My understanding is that rock wool or fibre glass treat all the frequences above the "cut off" in lack of better word. But you don't need as thick layer to treat the higher frequences.

Regarding the monitorplacement (you probably gonna get as many suggestions as there are walls in your room ) but I would probably face the short wall to the right. Also place your monitors symetric. Now they seem to be more to the right? But most importent, listen to how it sounds.

Good luck!

/Cojo

[jyc]

Hey cojo,

Thanks for the reply. In that case I think i might just build a few of those u made and scatter them around the room.

As for monitor placement, I'm planning to place them as the photo since I don't think I can treat the shorter walls: on one side there's a big window which I do need it opened quite frequently and the other side a cupboard that's built into the walls ...

Quite a few restrictions hey?


Jyc.

[matt thomas]

hey, I'm meeting with an architech on monday about setting up an acoustics consultancy in hong kong on monday!

but free advice for now..

Just raw rockwool will absorb all frequencies, the thicker stuff will absorb more bass but pretty much the same amoun of highs.

The thing is you mostly want bass absorbation. High frequencies tend to disapate by themsleves anyway.

The one place you may want to absorb highs is at the point where a signal from your monitors will bounce off a wall to you ears. (you can check for this spot by holding a mirror up to the wall and looking for the reflection of your monitors)

"nearly a cube" is fine, compared to a real cube, you may have problems because it is a small room though, but hey, you live in hong kong.

yeah, try and keep everything symetric doen the center, and prefereably speakers agains the short wall if at all possible

narco

[jyc]

Originally Posted by narco

hey, I'm meeting with an architech on monday about setting up an acoustics consultancy in hong kong on monday!

but free advice for now..

That's great news! Will definitely use your service when I advance enough to open my own studio

And also, good luck!

JYC

Edit: How did I forget to say thanks! :D

[Joel DuBay]

JYC,

First of all, our hats off to you on your DIY project. You can now build bass traps and acoustic panels that are functionally as good if not better than treatments costing up to a couple hundred bucks a piece.

Indeed, thickness and mass determine the amount of absorption at the low end of the spectrum and treating modes (low end standing waves) is what you want to do. If the space is tight, the inclusion of some broadband (low and hi frequency absorption) may be of some benefit.

Read more about early reflections here: EARLY REFLECTIONS EXPLAINED

If I view your diagram correctly the first thing I would do is make your listening position 180 degree from where it is now (assuming you can), and place your ears at about 1/3 the distance from the wall in front of you. (38%-40%) is a rule many have come to use as a standard listening position from the front wall.

Next, using your rockwool or miner fiber (at 4" thickness) treat your vertical corners and additional corners according to how much time and material you have. Horizontal corners are good places to trap bass as well.

If you can shoot me some photos of your room, I would be happy to make up a
3D sketch of your room and show you were to place your DIY traps once they are finished.

Materials:

Rockwool 4-8lb pcf
Mineral Fiber (OC703) 3-6 lbs pcf

Fabric (pick something you like and can live with) The more pourous it is, the more high frequency you will absorb and the "deader" your room may sound.

Frame: Why bother? You can add absorption by leaving the sides open (uncovered by wood). Utilizing a wood frame or something from IKEA may make it look cooler, and that counts too.

Number of units: 8-12 would be a good start according to your diagram. But, if I have photos, I will know better what to advise.

How to build DIY Bass traps: Search these sources:

Sound On Sound Acoustical Forum

Studio Tips Acoustical Forum


John L Sayers Acoustical Forum


BassTraps Network (This forum is not yet underway, but will be very, very soon and is completely non-commercial and intended so that DIY'ers can share their ideas and plans)


And of course, here at the famed Gearslutz forum


Shoot me some pics, and I'll get you a cool drawing my friend,

Good luck,


Joel DuBay
Ready Acoustics LLC
www.readyacoustics.com

[Glenn Kuras]

Joel gave you some good advise, but just to add you may want to think about building a frame if it is only 4 pound. It really will sag if you do not.

Glenn

[MB]

I learned so much from reading Ethan Winers articles. Finally I made my own traps with 5"compressed stone wool panels.
http://realtraps.com/articles.htm
Regards
Martin.

[bpape]

One slight correction to the otherwise excellent advice Joel gave you.

Sit your ears at 33% or 38% - preferably 38%. 40% actually has some nasty issues in a rectangular room do to axial mode interaction coupled with some of the less intense tangential and oblique modes.

Bryan